Fog inhibitors for photographic emulsions



Patented 1 0, 1939 FOG mnnm'ons roa rno'rocmrmc EMULSIONS I Samuel E. Sheppard and Waldemar Vanselow. Rochester, N. Y., assignorsto Eastman Kodak Company, Rochester,

New Jersey N. Y.', a corporation of I No Drawing. Application January 3, 1937, Serial No. 119,660

2 Claims.

This invention relates to fog inhibitors for photographic emulsions and to photographic emulsions containing them.

It is .known that photographic emulsions par- 5 ticularly-ultra-sensitive emulsions, or those containing color sensit 'zers exhibit a tendency toforma deposit vof silver inthe emulsion. This deposit extends more or less uniformly over the entire emulsion and is known as fog. Photographic fog is of two types, local and general. Local fog is formed by exposure of the film orplate at undesired points, as by a light leak in ways.

tions of high temperature or unusuallylong time of storage. The nature of the emulsion, as

where emulsions are highly sensitive may also produce'chemical fog, as well as the conditions of development of the emulsion, as by development for protracted periods of time or at temperatures above normal. Highly sensitive emulsions are more likely to fog than those of lower sensitivity, owing to the small amount of energy required to make a silver halide grain developable. We are concerned primarily with general or chemical fog.

The principal objectof the present invention is to provide fog inhibiting agents for photographic emulsions which decrease the tendency of the emulsions to form general or chemical fog and, therefore, increase its stability. A further object is to provide fog inhibiting agents which do not markedly lower the sensitivity of the emulsion. These objects are accomplished by 'incorpo rating in the emulsion suitable amounts of a morpholine compound, such as phenyl morpholine.

We have found that not all morpholine com- 40 pounds are useful for preventing the fogging of photographic emulsions, but only certain of the morpholine compoundsserve to inhibit the fogging tendency without lowering the sensitivity of Y the emulsion. For example, while phenyl morph oline has definite fog inhibiting value, compounds such as ethoxy ethyl morpholine have no definite value for this purposewhen used under the same conditions as phenyl morpholine. 1

A compound which we have found useful h 5.0 the following structural formula:

Phenyl morpholine cut-on, Q 0/ 7 0 CHr-CIh as compared with a similar emulsion'to which no Phenyl morpholine was found to give very good stabilization at a concentration of about 0.02

, ram per 1000 cc. of emulsion and also at concentrations as high as-4 grams per 1000 cc. of emulsion. Variation in the quantity necessary 5 depends upon the type of emulsion, its hydrogen ion concentration, the amount of halide present,

and on other factors.

It is to be understood that more or less of the anti-foggant agent and the amounts stated 10 above may be used. Generally, however, if a greater amount is used in the emulsion, either no increased fog inhibiting. effect is obtained or there is a loss in sensitivity of the emulsion. The fog inhibiting agents are incorporated by 15 mixing them with any suitable solventwhich is inert with respect to the sensitive emulsion, such as ethyl alcohol or other liquid in which the compound was soluble. An ethyl alcohol solution of 1% strength of phenyl morpholine was found to 20 be suitable for incorporation of the compounds which we propose to use.

The following example which is by way 01' lllustration only indicates methodsof incorporating the fog inhibiting agents inphotographic 25 emulsions according to our invention.

Example I A gelatino-silver halide negative, emulsion 30 which had been made in the usual way was heated on a water bath to a suflicienttemperature to melt it, To c.1000 cc. portion of this emulsion there was added a solution of cc. of ethyl alcohol containing 1 gram of phenyl morpholine.

The resulting solution was thoroughly mixed and 3 was coated on glass plates, dried and incubated for about a week at 60 C. 'to obtain a fog test. There was found'to be a marked fog inhibiting result through the use of the phenyl morpholine, 40

fog inhibiting agent had been added.

The fog inhibiting agents which we have described may be used in various kinds of photographic emulsions. In addition to beinguseful 45 in ordinary non-color sensitized emulsions they may also be used in orthochromatic, panchromaticiand X-ray emulsions. They may be used with or without color sensitizing dyes and'if used collodion; albumin or suitable cellulose organic derivatives or artificial resins.

It, is to be understood that we contemplate as included within ourinvention all'modiflcations and equivalents coming within the scope of the appended claims.

What we claim and desire to secure by Letters Patent of the United States is:

1. A photographic silver halide emulsion containing phenyl morpholine as an anti-'foggant.

2. A gelatino-silver halide emulsion containing as an anti-foggant, about 0.04 gram to about 4 grams per 1000 cc. of emulsion of phenyl morpholine.

SAMUEL E. SHEPPARD.

WAIDEMAR. VANSELOW. 

